A New Strategy for the Synthetic Assembly of Inorganic–Organic
Silver(I)-Polyoxometalate Hybrid Structures Employing Noncovalent
Interactions between Theobromine Ligands
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Abstract
A new
strategy for the synthesis of inorganic–organic silver(I)-polyoxometalate
materials was developed. The approach takes advantage of the ability
of purine bases to build strong networks using them as ligands to
silver(I). Its major experimental strong point is the facile preparation
of target compounds from aqueous solutions from basic starting materials.
Proof of concept was accomplished by using theobromine as the purine
base. Seven new compounds containing silver(I) theobromine building
blocks were characterized by single crystal X-ray diffraction: [Ag(thb)<sub>2</sub>]ClO<sub>4</sub> (<b>2</b>), [Ag(thb)<sub>2</sub>(H<sub>2</sub>O)]ClO<sub>4</sub> (<b>3</b>), [Ag(thb)<sub>2</sub>]<sub>2</sub>(H<sub>4</sub>V<sub>10</sub>O<sub>28</sub>)·3H<sub>2</sub>O (<b>4</b>), [Ag(thb)<sub>2</sub>]<sub>2</sub>(Cr<sub>2</sub>O<sub>7</sub>)·0.5H<sub>2</sub>O (<b>5</b>), [Ag(thb)<sub>2</sub>(H<sub>2</sub>O)]<sub>2</sub>(H<sub>3</sub>O)[Ag(β-Mo<sub>8</sub>O<sub>26</sub>)]·4H<sub>2</sub>O (<b>6</b>), [Ag(thb)]<sub>2</sub>[Ag(Cr(OH)<sub>6</sub>Mo<sub>6</sub>O<sub>18</sub>)]·2H<sub>2</sub>O
(<b>7</b>), and [Ag(thb)<sub>2</sub>]<sub>2</sub>(H<sub>3</sub>O)<sub>4</sub>[Ni(OH)<sub>6</sub>Mo<sub>6</sub>O<sub>18</sub>](CO<sub>3</sub>)·13H<sub>2</sub>O (<b>8</b>) (thb = theobromine). The purity of compounds <b>2</b>–<b>7</b> was confirmed by powder X-ray diffraction and elemental
analysis. They were also characterized by IR and UV/vis spectroscopy
and thermal analysis (DTA/TG). The main structural traits in all of
the polyoxometalate containing compounds are coordination polymers
running along the direction of one of the crystallographic axes. These
chains are interconnected by a framework of strong hydrogen bonds
and stacking interactions. The thermodynamic rationalization of these
crystal structure landscapes is thoroughly discussed
